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M ycorrhizae, symbiotic associations between fungi and plant roots, are
fundamental to improve nutrient and water uptake, as well as to increase tolerance to environmental stresses. To maximize the benefits of these associations,
it is crucial to know the best time to apply mycorrhizae. This article explores the
optimal times to mycorrhizate, emphasizing the importance of doing so early in the life
of plants.
What are mycorrhizae?
Mycorrhizae are symbiotic relationships where fungi colonize plant roots.
This interaction improves the uptake of nutrients such as phosphorus and nitrogen, and also helps
plants to better tolerate water stress, heat stress, salt stress, soil diseases
and insect attack.
Importance of applying mycorrhizae at the right time
Applying mycorrhizae at the right time is crucial to establish an effective relationship
between the fungus and the plant. The optimal times for mycorrhizae are those when the
plant roots are most active and capable of forming new associations. It is
important to understand that mycorrhizae associate with new roots.
Best times to mycorrhizate
During Planting
One of the best times to apply mycorrhizae is at the beginning of a plant’s
life, during planting. At this stage, young roots are in full
growth and are more receptive to colonization by mycorrhizal fungi.
Application Methods:
● Seed inoculation: Mix the mycorrhizal inoculant with the seeds prior to
sowing. This ensures that the emerging roots come into immediate contact with the
fungi.
● Seedline application: Apply the inoculant directly where the seeds will be sown.
During Transplantation
Another ideal time for mycorrhizal colonization is during the transplanting of plants from the nursery
to the field. Plants at this stage have young root systems that are still
developing, which facilitates mycorrhizal colonization.
Application Methods:
● Dipping Roots in Inoculant: Before planting, dip the roots of
seedlings in a solution of mycorrhizal inoculant.
● Application in Planting Hole: Place the inoculant in
the hole where the plant will be transplanted.
At the Start of the Growing Season
Applying mycorrhizae at the beginning of the growing season, when plants start their
vegetative cycle, can be very beneficial. At this stage, such as sprouting, plants are
starting to develop new roots and can establish mycorrhizal relationships in
an effective way. In established or adult plantations, it is advisable to choose this
phenological moment.
Application Methods:
● Irrigation with Inoculant: Mix mycorrhizal inoculant with water and apply via
irrigation at the base of the plants.
● Granule Application: Spread mycorrhizal granules around the plants and
irrigate to ensure they are incorporated and come in contact with the roots.
During Soil Preparation
In certain cases, applying mycorrhizae during soil preparation prior to planting or transplanting
can also be effective. This allows the inoculant to be distributed
evenly in the soil and ready to come into contact with the young roots as
they grow.
Application Methods:
● Mix with Compost or Compost: Incorporate the mycorrhizal inoculant into the compost or
compost before applying it to the soil.
● Direct Soil Application: Spread the inoculant on the prepared soil and
mix it lightly with the topsoil.
Factors to consider for a successful application
Crop Compatibility
Ensuring that the type of mycorrhiza is compatible with the crop is crucial. Arbuscular mycorrhizae
are suitable for most (over 90%) of agricultural crops, while ectomycorrhizae
are more specific for forest species.
Inoculant Quality
Using a high quality inoculant with a high concentration of mycorrhizal fungal spores
ensures effective and beneficial colonization.
Soil Conditions
It is important to consider soil conditions when applying mycorrhizae. A well aerated soil
with good structure facilitates the establishment of mycorrhizae.
Conclusion
The best time to apply mycorrhizae is at the beginning of a plant’s life, or at a
time when many new roots are being emitted. Either by coating the
seeds, during planting, transplanting, at the beginning of the growing season (sprouting) or
during soil preparation. Applying mycorrhizae at these specific times
maximizes the likelihood of successful colonization and ensures that plants can
fully benefit from this symbiotic association. By understanding and correctly applying
these principles, growers can improve the health and performance of their
crops in a sustainable manner.
Agricultural Engineer and Product Technician